Nocturnal penile tumescence
Encyclopedia
Nocturnal penile tumescence (informally known as "morning wood" or "morning glory") is the spontaneous occurrence of an erection
of the penis
during sleep
. All men without physiological erectile dysfunction
experience this phenomenon, usually three to five times during the night. It typically happens during REM sleep.
The existence and predictability of nocturnal tumescence is used by sexual health practitioners to ascertain whether a given case of erectile dysfunction
(E.D.) is psychological or physiological in origin. A patient presenting with E.D. is fitted with an elastic device to wear around his penis during sleep; the device detects changes in girth and relays the information to a computer for later analysis. If nocturnal tumescence is detected, then the E.D. is presumed to be due to a psychosomatic illness
such as sexual anxiety; if not, then it is presumed to be due to a physiological cause.
The cause of NPT is not known with certainty. Bancroft (2005) hypothesizes that the noradrenergic
neurons of the locus ceruleus
are inhibitory to penile erection, and that the cessation of their discharge that occurs during REM sleep may allow testosterone-related excitatory actions to manifest as NPT.
Evidence supporting the possibility that a full bladder can stimulate an erection has existed for some time and is characterized as a 'reflex erection'. The nerves that control a man’s ability to have a reflex erection are located in the sacral nerves (S2-S4) of the spinal cord. A full bladder is known to mildly stimulate nerves in the same region. This mild stimulus which during the day is normally suppressed in adult males by competing stimuli and other distractions; during sleep with the absence of such factors could instigate a reflex erection.
The possibility of a full bladder causing an erection, especially during sleep, is perhaps further supported by the beneficial physiological effect of an erection inhibiting urination, thereby helping to avoid nocturnal enuresis.
Erection
Penile erection is a physiological phenomenon where the penis becomes enlarged and firm. Penile erection is the result of a complex interaction of psychological, neural, vascular and endocrine factors, and is usually, though not exclusively, associated with sexual arousal...
of the penis
Penis
The penis is a biological feature of male animals including both vertebrates and invertebrates...
during sleep
Sleep
Sleep is a naturally recurring state characterized by reduced or absent consciousness, relatively suspended sensory activity, and inactivity of nearly all voluntary muscles. It is distinguished from quiet wakefulness by a decreased ability to react to stimuli, and is more easily reversible than...
. All men without physiological erectile dysfunction
Erectile dysfunction
Erectile dysfunction is sexual dysfunction characterized by the inability to develop or maintain an erection of the penis during sexual performance....
experience this phenomenon, usually three to five times during the night. It typically happens during REM sleep.
The existence and predictability of nocturnal tumescence is used by sexual health practitioners to ascertain whether a given case of erectile dysfunction
Erectile dysfunction
Erectile dysfunction is sexual dysfunction characterized by the inability to develop or maintain an erection of the penis during sexual performance....
(E.D.) is psychological or physiological in origin. A patient presenting with E.D. is fitted with an elastic device to wear around his penis during sleep; the device detects changes in girth and relays the information to a computer for later analysis. If nocturnal tumescence is detected, then the E.D. is presumed to be due to a psychosomatic illness
Psychosomatic illness
Psychosomatic medicine is an interdisciplinary medical field studying the relationships of social, psychological, and behavioral factors on bodily processes and well-being in humans and animals...
such as sexual anxiety; if not, then it is presumed to be due to a physiological cause.
The cause of NPT is not known with certainty. Bancroft (2005) hypothesizes that the noradrenergic
Norepinephrine
Norepinephrine is the US name for noradrenaline , a catecholamine with multiple roles including as a hormone and a neurotransmitter...
neurons of the locus ceruleus
Locus ceruleus
The locus coeruleus , is a nucleus in the brainstem involved with physiological responses to stress and panic. It was discovered in the 18th century by Félix Vicq-d'Azyr....
are inhibitory to penile erection, and that the cessation of their discharge that occurs during REM sleep may allow testosterone-related excitatory actions to manifest as NPT.
Evidence supporting the possibility that a full bladder can stimulate an erection has existed for some time and is characterized as a 'reflex erection'. The nerves that control a man’s ability to have a reflex erection are located in the sacral nerves (S2-S4) of the spinal cord. A full bladder is known to mildly stimulate nerves in the same region. This mild stimulus which during the day is normally suppressed in adult males by competing stimuli and other distractions; during sleep with the absence of such factors could instigate a reflex erection.
The possibility of a full bladder causing an erection, especially during sleep, is perhaps further supported by the beneficial physiological effect of an erection inhibiting urination, thereby helping to avoid nocturnal enuresis.